The defect entry is information that correlates positions of defective clusters with positions of substitute sectors that are used in place of the defective clusters.
The temporarily recording of the defect entry is a process in which when a defective area is detected while data is recorded onto a write-once optical disc, a defect entry concerning the defective area is recorded into a temporary area. The reason why it is necessary to temporarily write the defect entry is as follows. In the optical disc, an area called Defect Management Area (DMA) for writing defect entries therein is preliminarily provided. However, it is not allowed in a write-once optical disc to write a defect entry into the DMA until the finalize process is performed. This is because once data is written onto a write-once optical disc, it is impossible to rewrite the data later. That is to say, once a defect entry concerning a defective area is written to the DMA, it is impossible to add or update data in the DMA even if another defective area is detected thereafter. For this reason, when a defective area is detected during a recording process, it is necessary to write a defect entry concerning the defective area into a temporary defect management area, or the Temporary Disc Management Structure (TDMS).
The document indicated below discloses, as a prior art, a technology for writing the temporary defective area list, or the Temporary DeFect List (herein after, TDFL) that includes a plurality of defect entries concerning defective areas.    Document 1: Japanese Patent No. 2671656 (FIGS. 3-6)